Bilateral identical periodontal pockets have been produced on contralateral tooth surfaces in rhesus monkeys. On one side the pockets were treated by either (1) open curettage (four animals),(2) apically positioned flap with osseous surgery (four animals), and (3) autogenous red marrow and cancellous bone transplants (four animals). The contralateral pockets remained as untreated controls. One half of the animals in each group (i.e., two animals) will be killed at one year after operation. Specimens will be processed by standard histometric techniques and subject to histometric analysis. This will permit comparison of efficacy of treatment procedures. The remaining animals will be killed three years after the date of operation. As soon as eight additional rhesus monkeys have periodontal pockets of adequate depth, different therapeutic procedures for pocket elimination will be studied. The design of the investigations will be the same as described above. The squirrel monkey model for marginal periodontitis will be used to assess histometrically whether simultaneous initiation of repetitive trauma and periodontitis results in loss of connective tissue and crestal alveolar bone greater than that in our previous studies. Knowing that the two etiologic factors, namely, plaque formation and jiggling are responsible for connective tissue and alveolar bone loss, we will study the ability of the periodontal structures to repair when one or both of these etiologic factors are removed.